Studies of powdered fertilizers or nutrients have shown them to be effective fertilizers, being essentially equivalent to sulfate applications. However, the practical considerations of applying powdered products on a field scale meant that these products have not been available to farmers and producers. For example, most oxide products come in high analysis (60-80 percent actual metal) while most micronutrients are applied in low units per land measure (e.g. 1-10 pounds actual per acre). Furthermore, many micronutrient products are applied in heterogeneous blends with other fertilizers (nitrogen phosphate etc.) These products and/or blends typically have densities in the 45-65 lb per cubic foot range. Existing micronutrient products are typically in the 95+density range meaning that they do not hold their integrity in the blend if it is transported over rough terrain or during extended storage as is common in agriculture. In addition, the higher density means that the nutrients are not spread evenly on the field.
Fertilizer pellets are well-known in the art. For example:
U.S. Pat. No. 4,343,751 teaches a clay agglomeration process which comprises a method of preparing clay pellets which are subsequently coated with a variety of different end products, including fertilizers. It is of note that the pellets are intended to maintain their shape while the coated material is released.
U.S. Pat. No. 5,851,261 teaches coating fertilizer pellets with polyurea which is intended to act as a slow release coating so that the fertilizer is released over a greater period of time.
U.S. Pat. No. 6,192,623 teaches a plant feeder which releases nutrients into the soil using slow release fertilizer pellets.
U.S. Pat. No. 6,001,775 teaches a water soluble fertilizer tablet which is structured to disintegrate in a stream of water for subsequent application as a liquid. In addition, the fertilizer is combined with herbicide.
U.S. Pat. No. 5,030,267 teaches a controlled release fertilizer comprising a calcium metasilicate which is coated with fertilizers or other compounds.
U.S. Pat. No. 6,046,277 teaches a polymer for coating pharmaceutical or agrochemical pellets which comprises polyvinyl acetate in mixture with n-vinylpyrrolidone.
Thus, the prior art teaches pellets which are either arranged to be dissolved for use as liquid fertilizers or are arranged to dispense fertilizers over a long period of time. However, the prior art does not teach a fertilizer which combines the advantages of a powder fertilizer with the ease of application of a pellet.